Muffler attachment for telephones



March 10. 1925. 1,529,538

A. S. CARMAN ET AL MUFFLER A'gTACI-IMENT FOR TELEPHQNES Filed June 7, 1924 INVENTOR V TTORNEY Patented Mar. 10, 1925. 1,529,538 UNITED STATES PATENT OFFICE.

ALBERT S. CARMAN, OF NEW YORK, N. Y., AND JOSEPH A. PERIN, JR, OF EAST ORANGE, NEW JERSEY.

MUFFLER! ATTACHMENT FOR TELEPHONES.

Application filed June 7, 1924. Serial No. 718,455.

To all whom it may concern. The present invention includes an attach- Be it known that we, ALBERT S. CARMAN ment formed to be mounted in enclosing enand JOSEPH A. PERIN, Jr., citizens of the gagement with the telephone mouthpiece 11 United States, and residents, respectively, of at one end and projecting horizontally New York, in the county of New York and therefrom to provide a tubular member or 0 State of New York, and of East Orange, in casing through which speech is conveyed the county of Essex and State of New Jersey, from the attachment mouthpiece 1:2 to the have invented certain new and useful Imtelephone mouthpiece 11.

provements in Muffler Attachments for Tele- In order that a person using the telephone 10 phones, of which the following is a speci- 12 may talk without his speech being over- 65 tication. heard by persons nearby, the mouthpiece 12 This invention relates to devices for renis provided into which the lips of the user dering telephone conversations inaudible to are pressed in the course of conversation. persons in the neighborhood of the transmit- In order to insure the muliling or silencing 5 ting telephone. of the speech to a sufiicient degree to pre- 70 The invention includes a sound receiving V n i s being overheard by unauthorised d lif i d i d i d h tpersons, the silenc ng device isfoianed with t h d t a t d d t l h th i a double wall consisting of an inner wall 13 The device is itself equipped with a mouthn EH1 Outer l 14 Spaced apart to P piece i t whi h th user may 11; with t vide an annular air chamber 15 wholly enpossibility f hi conversation b i Overclosing the side walls of the inner speech heard by persons nearby, An expanding COllYQfflIlg tubular member 13. In Order t0 formation of the inner wall of the device Permit the user to employ relatively low from the mouthpiece to the telephone protones in talking into the mouthpiece 12, the

vides a sound amplifying function which 1: tubular member 13 is given an ex- 80 permits the employment of a relatively low pending formation from the region of the voic on th art of th sp aker, mouthpiece 12 to its other end 16 adjacent Another feature of the invention resides the telephone mouthpiece 11. The effect of in the provision of a double wall coiistructhe expanding formation of the tubular tion providing an annular air chamber member 13 is to amplify the sound waves which acts as a sound insulating means and received therein and to thereby deliver to which communicates with the interior of the the mouthpiece 11 of the telephone sounds device and the surrounding air to form a Whose loudness has been increased between tortuous passage which will permit fluctuatheir point of reception at the mouthpiece 35 tions of air into and out of the device and at 12 and the transmission to the telephone the same time prevent the escape of sound mouthpiece 11.

waves. The provision of the air chamber 15 in en- Othel features li lmentlon include closing relation to the amplifying sound the ready removability of the mufihng wave conveying member 13 not only acts as tachinent from operative p9Sl l0 I1 thI'OHgh a muffler or silencer with relation to the h use of a telescopic p 1 00111160" sound conveying member 13 but by the protion. vision of openings 17 in the inner member In the drawings, in which a preferre near one end thereof and openings 18 in the form of the invention has been selected for Outer 11 member 14 dj h Opposite illustration, end of the chamber 15 any tendency that Flgure 1 15 a V 1I1 S1616 elevation of a would otherwise be present to deaden or sound silencing attachm t e y g the distort the speech is overcome since the invention. openings 17 and 18 permit the oscillation of 1* igure 2 IS a View in vertical section f air into and out of the interior of the speech the device shown in Figure l. conveying member 13 to maintain a balance Referring to the drawings for a more deof pressure within and without the chamtailed description of the invention, a standher. This prevents fluctuations of pressure ard type of telephone transmitter is shown within the member 13 which would interfere at 10 and is supplied with the usual mouth with the free propagation of speech. At piece 11 projecting horizontally therefrom. the same time the placing of the openings 1w 17 out of alinement with eachother pro vides a relatively tortuous-passage through which the air must fluctuate and in thisway prevents the escape of soundwaves from the interior of the member 13 to the external air.

Another feature of the invention resides, in the particular construction of the silenc- By this construction it will beseen that the sound silencing device can be readily slipped from its position in theouter end of the supporting member 20 whereupon the telephone may housed in the ordinary way without resort to the silencing device.

What we claim is 1. In a device for preventing the unauthorized overhearing of telephone conversations, a supporting'member having enclosing and cushioning engagement with the transmitter mouthpiece of a standard telephone, a voice transmitting and amplifying member of expanding formation having a readily detachable slip-j oint connection with said supporting member, the outer end of the amplifying member being provided with a mouthpiece, a casing enclosing the amplifying member and spaced therefrom to form a sound insulating chamber surrounding the amplifying member, saidiamplifying member being provided with ports adjacent the mouthpiece and said casing being provided with a port adjacent the point of connection with the supporting member, said ports being in unaligned position whereby to provide a tortuous passage which will trap sound waves but permitting fluctuations of air pressure to pass into or out of the amplifying rh a mber.

2. in a device for preventing the unau: thorized oi'erhearing of telephone conversations, a two-part shielding device comprisin a supportadapted to have a cushioned and air-tight enclosing engagement with the transmitting mouthpiece of a standard telephone, and asound amplifying part having a readily detachable slip-joint connection ith the supportin member at itsenlarged end, a substantially cylindrical casing enclosing said amplifying part and spaced therefrom to form a sound insulating chamber surrounding the amplifying part, the smaller end of the amplifying part being provided with a mouthpiece, said amplifying part being provided with ports adjacent said mouthpiece, said casing being provided with ports adjacent said joint, and said casing having a constricted formation adjacent said mouthpiece to facilitate the use of the mouthpiece.

ALBERT S. GARMAN. JOSEPH A. PERIN, JR. 

